In many industries and applications various types of fluid and flow conditioners are used. Fluid and flow conditioners relevant for the invention are mechanical devices possessing an adjustable physical restriction to flow. Hence, common for fluid and flow conditioners relevant for the invention is that the conditioning process is accompanied by a reduction of the pressure of the flowing fluid. Sometimes adjustable throttling valves are used as flow and fluid conditioners.
A flow conditioner is herein defined as a device used to optimize the properties of the flow to achieve certain equipment, instrument or process benefits. Relevant for the invention are flow conditioners possessing a fixed or adjustable restriction to flow whereby the flow conditioning is accompanied by a fluid pressure drop. For example, flow conditioners are sometimes used to enable accurate measurements of the rate of flow of a fluid passing along a pipe by stabilizing the flow and removing non-uniformities which affects both mean flow and turbulence structure. Typical examples of such flow conditioners are U.S. Pat. No. 5,341,848, U.S. Pat. No. 5,762,107, EP 1188935 A2 and EP 0808425 A1. Other flow conditioners may be used to reduce cavitation or erosion effects of a flow, like the device described in EP 2447466 A2.
A fluid conditioner is herein defined as a device used to optimize the properties of the fluid to achieve certain equipment, instrument or process benefits. Fluid conditioners come in numerous variants like for example heaters, coolers, coalescers, mixers and separators. Relevant for the invention are fluid conditioners possessing a fixed or adjustable restriction to flow whereby the fluid conditioning is accompanied by a fluid pressure drop. Examples of fluid conditioners are described in US 2010/0314327 A1, US 2010/0314325 A1 and U.S. Pat. No. 2,005,515.
Throttle valves are adjustable mechanical devices often installed with the main objective to control or regulate the flow rate or pressure of a flowing fluid. In performing the main duty, however, conditioning of the fluid or flow is often side effects. Sometimes the fluid conditioning effect is a wanted effect and an effect very important for a downstream process or equipment. Examples of such valves and applications are EP 1831628 B1 and U.S. Pat. No. 3,457,730 describing so-called Joule-Thompson valves where the gas cooling effect, due to the valve pressure drop, is very important for downstream processes. Another example is when a throttling valve is used as a fluid mixer, like in U.S. Pat. No. 5,971,604, where the mixing effect is the wanted effect and where the pressure drop is a side effect.
Most often however, the fluid and flow conditioning effects caused by a throttling valve are unwanted and uncontrolled, causing problems for the valve itself or for the downstream piping, process or equipment. Examples of such are many and particularly found in petroleum production and processing where the use of throttling valves is widespread. Choke and control valves are throttling valves where the main duty normally is to control the flow rate or pressure of a flowing fluid. Choke and control valves may have both wanted and unwanted flow and fluid conditioning effects.
Choke valves are used at wellheads in order to choke the well flow and to regulate the production rate of the petroleum fluids. Typical reasons for using a choke valve is to avoid sand production or too high water cut in the flow from the well, in which situations choking the valve can reduce sand production or high water cut. However, a typical choke valve has a high shear, mixing and droplet breaking effect on the fluid, which can be a disadvantage for subsequent processing.
The fluid from a wellhead is typically routed to a first stage separator, where the fluid is separated into gas, oil or condensate and water. The phases oil or condensate, water and gas are typically processed further. For example, the oil or condensate should be clean enough for transportation and further use in refineries and for other purposes, the gas should be dry and clean enough for export or sale and the water should be clean enough for dumping or reinjection.
Between processing steps, it can be required to have flow or pressure control valves or devices. A problem not receiving much attention is the effect of flow or pressure control valves upstream separation equipment. The effect is often that droplets in the flowing fluid are broken up into smaller droplets and the different phases in the flow are mixed thoroughly. However, this has the effect of reducing the efficiency of downstream separation equipment.
Sometimes when throttling valves are used in subsea petroleum applications there is a transportation pipeline downstream from the valve. The transportation pipeline may lead to either a subsea or topside separation process system, where the location of the separation process may be distant from the valve. Because of the mixing and emulsifying effect of the throttling valve the fluid mixture may have an increased viscosity, which increases the resistance of the fluids to flow. With a higher fluid viscosity the pressure loss in the transportation pipeline increases. Hence, due to the emulsification effect the valve may increase the energy requirement in connection with downstream transportation.
Typical prior art pressure reduction valves are needle valves or valves of similar designs with a valve element that can be moved toward or from a seat, diaphragm and spring valves, gate valves, ball valves and plug-cage valves. A typical plug-cage choke or control valve may comprise two longitudinally coaxial elements movable relatively to each other and with the cage having a number of bores which the plug match/block or not so as to regulate the choking effect by adjusting the effective flow bore cross section area, such as described in patent publications WO 2010020741 A1, WO 2009093035 A2 and WO 2007024138 A1.
The prior art throttling valves are often small in size and weight, which is considered an advantage and therefore is pursued.
Common for prior art throttling valves like choke and control valves is that the flow rate or pressure control is accompanied by a reduction of the pressure of the flowing fluid. The reduction in pressure implies that turbulence and shear forces are created within the flow of the valve and the turbulence and shear forces have a conditioning effect on both the fluid and the flow. Typically, the fluid and flow conditioning effects are not beneficial and the fluid and flow conditioning effects are not controlled.
A demand exist for a pressure reduction valve or device having a controlled flow conditioning effect, or a pressure reduction valve or device having a controlled fluid conditioning effect, or a pressure reduction valve or device having both controlled flow and fluid conditioning effects.
Hence, a demand exist for a combined throttling valve and fluid conditioner, or a combined throttling valve and flow conditioner or a combined throttling valve, fluid conditioner and flow conditioner, optimizing the duty of the valve itself whilst providing benefits for downstream process steps or equipment efficiency.
A demand exists for a pressure reduction valve or device having a droplet coalescing effect on droplets in a flowing fluid phase, preferably having a coalescing effect in many modes of operation, dependent on the incoming fluid and required pressure reduction. Such valve would be beneficial for use upstream separation equipment, and the objective of the invention is to provide such valve.
Reduced degradation of polymer solutions or other shear sensitive fluids is a further desired effect of the present invention. In many applications shear sensitive fluids are throttled across a choke or control valve where the throttling causes a degradation of the shear sensitive fluids. One example of such application is the use of polymers in enhanced oil recovery operations where water is injected to the reservoir. The injection water may be produced water, co-produced with oil and gas from the reservoir, or seawater. The water is injected to flood oil from injection wells towards production wells of the reservoir. To increase the flooding efficiency polymers are sometimes added to the water to increase the water viscosity. One challenge is then that the polymers, which often are long-chained molecules like hydrolyzed polyacrylamide, are broken in injection choke valves. To accommodate this problem many different solutions have been developed. U.S. Pat. No. 4,276,904 describes an adjustable device based on tubes arranged as coils for controlling the flow rate and pressure of polymer solutions. WO2012001671 reveals also a tube based, adjustable throttling device, but where the tubes are a parallel arrangement rather than coils. Paper SPE 106693 describes laboratory test results of a similar solution then used to reduce the breaking of oil droplets in a water flow. Other solutions to reduce degradation of polymers during adjustable flow control are provided by U.S. Pat. No. 4,510,993, U.S. Pat. No. 3,477,467 and U.S. Pat. No. 4,617,991.